Ok, have had this 95 Tahoe since Dec. Ran good but had an exhaust leak at the manifold. Bad "donut". Had this prob on my 95 k2500 last year.

Both manifolds replaced and new "donuts"/heat shields and such the other day. Got it back and now I have what seems to be a miss. I changed the plugs/wires/cap/rotor AFTER the exhaust repair and still have miss. Vibration and loud exhaust sound at speed/load. Seems worse once it warms up. Seems like wires crossed but they are not. Did not run like this b4 new manifolds. Was loud but ran OK.

The truck ran OK before the manifold exhaust repair. I changed the plugs and wires AFTER the repair and only after I noticed it was not running right. Planned on tune up anyway.

There was no change in how it ran after tune up. The old cap was burnt to high heaven. No contact left at center. All the points inside cap were covered in heavy corrosion. Plugs were brown on one side of electrode.

Do not think it had to do with the tune up parts. Ran the same before and after.

Being a 95 it's a 1 year only deal. It's not OBD1 or OBD2 kind of like a half and half. This will be extremely hard to diagnose over the net.

1st, is the check engine light on? if so what are the codes?

2nd, is it a light misfire? or does it feel like it's dropping a cylinder?

Seeing as it happened right after the manifolds were replaced, it sounds like a crossed ignition wire, they need to be removed to get the manifold off and could easily be put back on incorrectly, but you said they are not. And changing the cap rotor plugs and wires didn't change anything?

Did they have to torch any of the old bolts out? They could have heated a cylinder head to much to the point one of the exhaust valve seats fell out and is holding a valve open.

Fuel pressure could be too low, Does it have a long crank situation?

One thing that comes to mind with the Vortec motors is the distributor bushing wear out. The distributor shaft wobbles and causes a rolling random misfire. Some or even all the cylinders can misfire. Another thing is the spider injectors clog and stick causing a lean condition on specific cylinders.

Really hard to tell without seeing the truck and not having a scan tool hooked to it.

__________________

There is no such thing as Too Many MontesMember of the Motley Cruisers Car Club

I pulled all the wires and ran them direct from distributor to each plug one by one. Little chance of me running them wrong.

The miss is kind of like a chugging. Nice vibration in the whole vehicle. There are no codes, check engine light not on at all. Once you put it under load, it gets louder. Almost like there is an exhaust leak again but there is not. Runs semi ok till it gets up to operating temp. Then is has hard acceleration, vibration, loss of power. If you eve ran a vehicle with the exhaust off the manifolds it feels like that without all the noise.

I know it is hard to diagnose over the net. Just looking for start point. Taking it back to the shop that did it so he can maybe play detective.